This invention relates to a machine of the type having a tool for forming holes in a substantially flat and horizontal work sheet. The tool may, for example, be a punch, a plasma-arc torch or a laser. A machine having both a punch and a plasma-arc torch for forming holes in a work sheet is disclosed in Brolund et al U.S. Pat. No. 4,106,183.
In the machine disclosed in that patent, the work sheet is supported on a table which is adapted to be moved in a fore-and-aft direction on a base in order to shift the work sheet to various fore-and-aft positions beneath the tool. Located at the rear of the table are at least two laterally spaced clamps for gripping the rear edge portion of the work sheet. The clamps are supported by a carriage which is adapted to be moved laterally on the table. When the carriage is moved laterally, the clamps shift the work sheet laterally across the table in order to move the work sheet to various lateral positions beneath the tool.
In a somewhat different type of machine, fore-and-aft positioning of the tool and the work sheet is effected by bodily shifting the tool while holding the work sheet in a stationary position. Lateral re-positioning of the work sheet, however, is effected by a carriage having clamps which operate in the manner described above.
The clamps usually are spaced laterally from one another by a distance determined by the width of the work sheet. When the machine is changed over to handle a work sheet of a different width, the clamps must be adjusted on the carriage to increase or decrease the lateral spacing between the clamps. Also, it frequently is necessary to adjust the clamps laterally on the carriage in order to prevent the clamps from interfering with the formation of holes in certain areas of the work sheet.
Heretofore, lateral adjustment of the clamps on the carriage has been effected by manually releasing each clamp from the carriage, by manually shifting the clamp along the carriage to the desired new position and then by manually re-locking the clamp to the carriage. Such manual adjustment requires the machine operator to go back and forth between the front of the machine where the controls are located and the rear of the machine where the clamps are located. In large machines having sheet loading and unloading equipment, the operator must walk a considerable distance between the controls and the clamps. The travel time, as well as the time required to actually adjust the clamps, results in a significant amount of down time for the machine. In addition, the time spent by the operator in adjusting the clamps is not, of course, available for the performance of other duties.